Air circuit breakers as described within U.S. Pat. Nos. 3,095,489 entitled "Manual Charging Means for Stored Energy Closing Mechanisms of Electric Circuit Breakers" and 3,084,238 entitled "Ratchet Mechanism for Charging a Closing Spring in an Electric Circuit Breaker" include operating mechanisms that are mainly exposed to the environment. Since the air circuit breakers are rated to carry several thousand amperes of current continuously, the exposure to convection cooling air assists in keeping the operating components within reasonable temperature limits.
Such air circuit breakers are usually provided with a motor operator such as described in U.S. Pat. No. 4,167,988 entitled "Ratcheting Mechanism for Circuit Breaker Motor Operator" or a manual handle as described in U.S. Pat. No. 3,729,065 entitled "Means for Charging A Stored Energy Circuit Breaker Closing Device" for charging the powerful closing springs contained within the air circuit breaker operating mechanism.
When the circuit breaker closing springs are brought to their fully-charged conditions, it is important that the springs do not become inadvertently discharged while an operator has hold of the charging handle in order to avoid damage to the ratchet mechanism and the associated air circuit breaker contacts. An early arrangement of a latching means to prevent rotation of a closing springs charging handle is found in U.S. Pat. No. 4,475,021 entitled "Air Circuit Breaker".
When the circuit breaker closing springs are completely charged, the holding pawl is removed from the charging gear to allow the charging shaft to rotate in the reverse direction when the circuit breaker closing button is activated, as described in U.S. Pat. No. 8,883,351 entitled "Ratcheting Mechanism for Industrial-Rated Circuit Breaker" filed on May 27, 1997.
Although the circuit breaker contacts along with the circuit breaker operating mechanism are located in air, the position of the contacts behind the circuit breaker enclosure makes it difficult, if not impossible, to determine the true status of the circuit breaker contacts relative to the ON and OFF conditions
One arrangement to determine the condition of the circuit breaker contacts is to provide a viewing window in the front cover of the circuit breaker and position a target indicator under the window to display the ON/OFF status. The target indicator mechanically links with the circuit breaker closing shaft to accurately position the ON/OFF indicia with respect to the circuit breaker contacts.
U.S. Pat. No. 5,823,3238 entitled "Circuit Breaker Contact Position Indicating Unit" filed on Feb. 3 1997 and U.S. patent application Ser. No. 08/878,598 entitled "Contact Position Indicator for an Industrial-Rated Circuit Breaker" filed on Jun. 19, 1997 describe such visual contact indication in high-ampere industrial rated type circuit breakers. The components interconnecting between the target indicator and the circuit breaker operating mechanism are designed to meet the high-ampere requirements.
With lower ampere-rated industrial circuit breaker assemblies, the limited space available does not readily lend to the use or application of similar position indication components.
One purpose of the invention, accordingly, is to describe a simple target indication arrangement for use with industrial-rated circuit breakers of lower ampere-rating.